A computer cabinet may enclose and hold parts of a computer system, including disk drives, power supplies, fans, central processing unit (CPU) boards, peripheral boards, and the cables used for connecting the parts together. Sometimes the cables, particularly the cables associated with the power supplies, are routed to other parts of the system by connecting them through a printed wiring board (PWB) or a printed wiring assembly (PWA) located at the bottom of the cabinet or other fixed non-removable part of the cabinet walls such as its side walls. CPU and peripheral boards typically are plugged into a backplane connector. The connector may be of the plug and socket type. However, as shown in FIG. 1, the above-mentioned boards may be mounted to the computer cabinet on standoffs and fastened with fastening hardware such as screws. The standoffs keep the bottom of the board from touching the bottom of the cabinet, thus preventing short circuits on the board. Typically at least four standoffs are used, one for each corner of the board. Often, additional standoffs are placed near the center of the board to provide additional support and prevent flexing of the board when connectors are plugged in and pulled out.
One problem with using fastening hardware such as screws to attach the parts to the computer cabinet is that the fastening hardware may be difficult to access during the manufacturing and servicing of the computer system. The fastening hardware is typically very small because computer cabinets are tightly packed so that the size of the system is small enough to fit on or under a desk. In addition, the parts contained in the computer are tightly packed so that the fastening hardware is difficult to reach without a significant amount of effort. When a technician replaces a part which is fastened to a computer cabinet with screws, he typically reaches into the computer cabinet with a screwdriver in order to remove the screws which attach the part to the computer cabinet. Even if the technician can access the screws easily enough to unscrew them, he may drop the screws into the computer system as he tries to remove the screws or as he tries to remove the part itself. If he loses the screw or forgets to remove it, the screw may cause a short circuit in one of the components of the system the next time the computer is powered up. As a result, replacing parts in the computer system is a time-consuming and frustrating process.
Another problem with fastening a board to a computer cabinet using screws is that excessive flexing of the board may occur as a result of forces applied toward the board and away from the board as connectors are plugged in and pulled out of the top of the board. The amount of flexing may be sufficient to cause failures when the board includes connectors which require high insertion and extraction forces, for example, power supply connectors. Attempts to solve this problem include adding standoffs to the center of the board to provide additional support. However, adding standoffs requires adding more screws, thus increasing the number of screws a technician needs to remove when replacing the board. Another disadvantage to this solution is that the additional screw holes required on the board reduce the area in which circuit traces may be routed because a portion of the board must be reserved for the holes. This reduces the amount of circuitry which may be placed on the board and also reduces the amount of flexibility the board designer has in determining where the circuit traces should be located.
Advantages of the invention will be set forth, in part, in the description that follows and in part, will be understood by those skilled in the art from the description or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims and equivalents.